#ifndef XRPL_APP_PATHS_RIPPLELINECACHE_H_INCLUDED
#define XRPL_APP_PATHS_RIPPLELINECACHE_H_INCLUDED

#include <xrpld/app/ledger/Ledger.h>
#include <xrpld/app/paths/TrustLine.h>

#include <xrpl/basics/CountedObject.h>
#include <xrpl/basics/hardened_hash.h>

#include <cstddef>
#include <mutex>
#include <vector>

namespace ripple {

// Used by Pathfinder
class RippleLineCache final : public CountedObject<RippleLineCache>
{
public:
    explicit RippleLineCache(
        std::shared_ptr<ReadView const> const& l,
        beast::Journal j);
    ~RippleLineCache();

    std::shared_ptr<ReadView const> const&
    getLedger() const
    {
        return ledger_;
    }

    /** Find the trust lines associated with an account.

       @param accountID The account
       @param direction Whether the account is an "outgoing" link on the path.
       "Outgoing" is defined as the source account, or an account found via a
       trustline that has rippling enabled on the @accountID's side. If an
       account is "outgoing", all trust lines will be returned. If an account is
       not "outgoing", then any trust lines that don't have rippling enabled are
       not usable, so only return trust lines that have rippling enabled on
       @accountID's side.
       @return Returns a vector of the usable trust lines.
    */
    std::shared_ptr<std::vector<PathFindTrustLine>>
    getRippleLines(AccountID const& accountID, LineDirection direction);

private:
    std::mutex mLock;

    ripple::hardened_hash<> hasher_;
    std::shared_ptr<ReadView const> ledger_;

    beast::Journal journal_;

    struct AccountKey final : public CountedObject<AccountKey>
    {
        AccountID account_;
        LineDirection direction_;
        std::size_t hash_value_;

        AccountKey(
            AccountID const& account,
            LineDirection direction,
            std::size_t hash)
            : account_(account), direction_(direction), hash_value_(hash)
        {
        }

        AccountKey(AccountKey const& other) = default;

        AccountKey&
        operator=(AccountKey const& other) = default;

        bool
        operator==(AccountKey const& lhs) const
        {
            return hash_value_ == lhs.hash_value_ && account_ == lhs.account_ &&
                direction_ == lhs.direction_;
        }

        std::size_t
        get_hash() const
        {
            return hash_value_;
        }

        struct Hash
        {
            Hash() = default;

            std::size_t
            operator()(AccountKey const& key) const noexcept
            {
                return key.get_hash();
            }
        };
    };

    // Use a shared_ptr so entries can be removed from the map safely.
    // Even though a shared_ptr to a vector will take more memory just a vector,
    // most accounts are not going to have any entries (estimated over 90%), so
    // vectors will not need to be created for them. This should lead to far
    // less memory usage overall.
    hash_map<
        AccountKey,
        std::shared_ptr<std::vector<PathFindTrustLine>>,
        AccountKey::Hash>
        lines_;
    std::size_t totalLineCount_ = 0;
};

}  // namespace ripple

#endif
